Odtnhj

I've just starting using Java Swing and I have a issue.
I tried to do a simple menuBar and a menuItem 'Exit', but before linking the button to the action the menuItem appeared, now that I've linked the button to a System.exit(0) action it disappeared. Help?
The code is the following:

in MainPanel (the autogenerated code from swing is excluded):

public void init() 
 initComponents();
 initActions(); 

 setLocationRelativeTo(null); 
 pack();
 setVisible(true);


private void initActions() 
 this.menuItemExit.setAction(Application.getInstance().getPanelControl().getActionExit());

In PanelControl:

public class PanelControl {

 private Action actionExit;


 public Action getActionExit() 
 return actionExit;
 



public class ActionExit extends AbstractAction

 public ActionExit()
 putValue(Action.NAME, "Exit");
 putValue(Action.SHORT_DESCRIPTION, "Exit from the application");
 putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke("ctrl e"));
 putValue(Action.MNEMONIC_KEY, KeyEvent.VK_E);
 

 @Override
 public void actionPerformed(ActionEvent e) 
 System.exit(0);
 

In Application:

private void init() 
 viewMainPanel = new MainPanel();
 controlPanel = new ControlPanel();
 viewMainPanel.init();

i think the problem is somewhere in here but i can't figure out where. any help?
(there's other code but i just put the more relevant part, also i translated the code from italian so i'm sorry if there are any problems or a few names dont match up)

private Action actionExit;


public Action getActionExit() 
 return actionExit;

Your actionExit variable is null.

Nowhere in your code do you create an instance of your ActionExit class.

Somewhere you need:

actionExit = new ActionExit();

Your design seems a bit complicated, I have no idea why you have a panel just to create an instance of the ActionExit class.

I would suggest you just create the ActionExit instance in your main class and get rid of the PanelControl class.

Instead of using an IDE to generate confusing code you should consider learning how to write the code yourself so you can better structure your classes. Read the section from the Swing tutorial on How to Use Menus for a working example to get you started.

A menu item has to be added to a Native Java Swing component. You have to add it to a JFrame. You can't add a MenuItem to a Panel. The Parent 'root' container in any Java Swing application is 'native' and a JFrame. Everything else in that container is 'drawn' into the rectangle using the look and feel of your choosing.

Then you CREATE a MenuItem using your TAbstractAction item. That object CAN be used to create a JButton, JMenuItem or ToolBar button. Keeping a reference to your TAbstractAction in your code, you can enable/disable the object and it implements an 'observable' pattern where it will enable/disable ALL UI controls you used to build with it. I actually wrote a Java Swing framework for doing Java Applications. It used to be on the Sun Open Source web site. If you wish I can put it up on GitLab for you to play with. Java Swing is nice but JavaFX should be the long term goal for UI on a JVM.

In your JFrame object you need to do this:

 _menuBar = new JMenuBar();

 // add controls to the frame
 setJMenuBar(_menuBar);

Then you need to add your 'exitMenuItem' to your _MenuBar control.
Cheers